Method and apparatus for operating an actuator

ABSTRACT

A drilling or flushing medium is used in the operation of an actuator for controlling an earth working device which uses the drilling or flushing medium for its operation as well. The actuator is acted upon by the medium , which can be retained in the actuator through suitable operation of a valve assembly, while at the same time can be supplied to the earth working device to execute a desired function. The valve assembly is hereby actuated by a separate switch.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the priority of German Patent Application, Serial No. 10 2006 016 613.2, filed Apr. 6, 2006, pursuant to 35 U.S.C. 119(a)-(d), the content of which is incorporated herein by reference in its entirety as if fully set forth herein.

BACKGROUND OF THE INVENTION

The present invention relates to a method for operating an actuator, and apparatus for carrying out the method.

Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.

Earth boring and laying of pipelines in the ground involves the use of tools or drill heads which can be controlled in various ways. Examples include the use of asymmetric drill heads which can be adjusted through turning at the hose, or a control of the head by means of an asymmetric jet of drilling liquid issuing out of the drill head. Control of the drill head may hereby serve for targeted change in the drill course or also to only compensate for variations in soil conditions. Conventional approaches, which use actuators in the area of the drill head or other equipment elements that are difficult to access in the ground, have all the basic problem that any control of the actuators, which are also situated inaccessibly in the ground, has to be carried out from ground level, e.g. using mechanical systems, electrical auxiliary lines, wireless communication, or a pressure medium source.

However, for a number of reasons, the various proposals are endowed with drawbacks and shortcomings relating to the effect that is hoped to be obtained but may not always be realized. For example, purely mechanical solutions oftentimes are difficult to operate in view of the conditions on the construction site and the forces and frictions caused during drilling.

There is a special need for the precise control to realize a compensation control for maintaining a straight drilling course in the ground, when laying sewage lines at slight gradient is involved, which are operated solely by the force of gravity. This requires high precision, in particular for the installed depth, because excessive deviations may result in deposits or clogging of the sewage pipe during later operation. Difficulties arose when installing lines into the ground because of the inability to install them in a sufficiently straight manner along the intended path. The vertical and horizontal rectilinearity always fluctuates more or less. These fluctuations oftentimes exceed the admissible tolerances, in particular when sewage lines are involved in very flat terrain, so that the installation using current horizontal drilling technique caused problems.

Known methods (open construction, auger equipments, etc.) operate very slowly. Open construction may damage in some circumstances high-quality surfaces which require repair after installation. Respective methods are known from WO 02/057590 A2, U.S. Pat. No. 6,668,946 B2, DE 196 05 983 C2, and DE 198 02 209 C2.

It would therefore be desirable and advantageous to provide an improved method and apparatus for operating an actuator to obviate prior art shortcomings.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a drilling or flushing medium is used in the operation of an actuator for controlling an earth working device.

According to another aspect of the present invention, an apparatus includes at least one actuator for controlling an earth working device, and a valve assembly for operating the actuator by means of a drilling or flushing medium.

The present invention resolves prior art problems by implementing an adjustment of the actuator (e.g. lift pad, cylinder, etc.) by the potential energy (pressure energy) of the provided drilling medium (e.g. bentonite). As a consequence, the actuator can be operated inside a drilling tool or expansion tool in the absence of any supply of separate control means (like e.g. electric energy or hydraulic pressure). The use of respective feed lines may also be omitted because the use of the drilling liquid, which exists anyway, as control means eliminates the need for additional supply lines and/or control lines which would have to be conjointly routed e.g. from drill rod section to drill rod section and respectively connected. Liquids that pose a hazard to the environment, like e.g. hydraulic oil, are not necessary so that a risk of soil contamination is avoided.

According to another feature of the present invention, the valve assembly may include a camshaft, and plural valves which are operated by the camshaft. Suitably, the valve assembly includes a cylinder which is operated by the fluid and operatively connected to the camshaft.

According to another feature of the present invention, the actuator may be configured as lift pad.

According to another feature of the present invention, the earth working device is constructed for advancing along a predefined drilling route, wherein a tool can be provided for correcting an advance of the earth working device to compensate for a deviation from the drilling course. Thus, the tool is able to correct any fluctuations of the drilling course in the absence of a separate supply of electric current or other control means.

According to another feature of the present invention, the valves may be spring-biased valves.

According to another feature of the present invention, the apparatus is suitable for carrying out any one of the operations selected from the group consisting of correcting a deviation of a drill head in a pilot bore, when the earth working machine is the drill head, correcting a deviation of an expansion head, when the earth working machine is the expansion head and lines are pulled in, opening and closing of valves or gates, operation of borehole tools, disengagement or engagement of tools in the ground, and moving out of a bore route for establishing branch lines or for exploration.

According to another aspect of the present invention, a method for operating an actuator for controlling an earth working device includes the steps of subjecting the actuator to a drilling or flushing medium used for the earth working device, and controlling an operation of a valve assembly such that the drilling or flushing medium is retained in the actuator, while at the same time is supplied to the earth working device for executing a desired operation.

According to another feature of the present invention, the controlling step can be realized by actuating a separate switch for adjusting the operation of the valve assembly.

According to another feature of the present invention, the valve assembly may include plural spring-biased valves which return to their initial position when a pressure of the drilling or flushing medium drops below a spring force which acts on the valves.

BRIEF DESCRIPTION OF THE DRAWING

Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which.

FIG. 1 shows a schematic illustration of a line and actuator arrangement according to the present invention, with the actuator assuming a moved-out position;

FIG. 2 shows a schematic illustration of the arrangement of FIG. 1 in a control state, in which the actuator assumes a position prior to moving out;

FIG. 3 shows a schematic illustration of the arrangement of FIG. 1 in a control state in which the actuator assumes a position prior to its return to an initial position; and

FIG. 4 shows a schematic illustration of a valve assembly for controlling operation of the actuator.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Throughout all the Figures, same or corresponding elements are generally indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.

Turning now to the drawing, and in particular to FIG. 1, there is shown a schematic illustration of a line and actuator arrangement according to the present invention for operating an earth working device, e.g. a drill head or an expansion head. The actuator, e.g. a lift pad, is positioned underneath a control gate and is constructed to be able to move out by pressure applied by a drilling liquid, which is used anyway for operation of the earth working device, after the control gate with the lift pad is transferred into the desired control direction by turning a drill rod into the hold direction of a freewheel. After conclusion of the control process, the control gate has to move back again (i.e. the drilling liquid must be removed from the lift pad/actuator). A further state involves drilling/expanding with the control gate/lift pad having been moved out. All three control states are realized through logic combination of three seat valves (check valves) 3, 6, 8 which are acted upon by springs 2, 4, 9, respectively, and locked alternatingly in the exemplified embodiment by a camshaft 10 which is also operated by the drilling liquid, as will now be described with reference to FIGS. 1-4.

FIG. 1 shows by way of example an expansion tool 5 which includes in prolongation thereof a non-rotating control gate which has been moved out via an actuator 1, e.g. a lift pad, by means of a drilling liquid pressure generated by a drilling liquid pump 7. The closed and locked valves 3 and 8 prevent escape of drilling liquid from the actuator 1. Valve 6 opened by the drilling liquid pressure allows a flow of drilling liquid to the expansion head 5. This state of the valves 3, 6, 8 is shown in FIG. 4.

In FIG. 2, the actuator 1 should be lifted with drilling liquid pressure. The drilling liquid pressure is initially reduced to 0 bar so that all valves 3, 6, and 8 are returned to the closed position by spring force applied by the spring 2, 4, 9. Turning in this exemplified embodiment of the camshaft 10, shown in FIG. 4, causes a locking of the valves 6 and 8. After the drilling liquid pump 7 is switched on, pressure builds up in the actuator 1, causing the actuator 1 to rise.

FIG. 3 illustrates the situation when the actuator 1, after use, should be returned to its initial position again. At first, the drilling liquid pressure is again set to 0 bar so that the valves 3, 6, and 8 are returned to the initial position by spring force applied by the spring 2, 4, 9. By continuing to turn the camshaft 10 about 120°, the valve 3 is locked. Valve 8 is opened by the ground pressure present at the control gate and thus at the actuator 1, and the drilling liquid is able to escape the actuator 1 into the soil. The locked valve 3 prevents a renewed expansion of the actuator 1 when the drilling liquid pump 7 is switched on so that the drilling liquid is able, without exception, to flow via the unlocked valve 6 to the expansion head 5.

FIG. 4 depicts a section through the valve assembly and the camshaft 10 used in this exemplary embodiment. The state described in FIG. 1 is illustrated here. The indexed switching of the camshaft 10 is implemented in this exemplary embodiment by a single-action cylinder (not shown) which is also operated by the drilling liquid. After decreasing the drilling liquid pressure to 0 bar, the drilling liquid pump 7 is suddenly switched on again. The controls and the springs 2, 4, 9 of the valves 3, 6, and 8 as well as an upstream faceplate cause actuation of the cylinder chronologically before the valves so that the camshaft 10 is indexed further.

While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. The embodiments were chosen and described in order to best explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein: 

1. A drilling or flushing medium for use in the operation of an actuator for controlling an earth working device.
 2. Apparatus, comprising: at least one actuator for controlling an earth working device; and a valve assembly for operating the actuator by means of a fluid selected from the group consisting of drilling medium and flushing medium.
 3. The apparatus of claim 2, wherein the valve assembly includes a camshaft, and plural valves which are operated by the camshaft.
 4. The apparatus of claim 3, wherein the valve assembly includes a cylinder which is operated by the fluid and operatively connected to the camshaft.
 5. The apparatus of claim 2, wherein the actuator is configured as lift pad.
 6. The apparatus of claim 2, wherein the earth working device is constructed for advancing along a predefined drilling route, and further comprising a tool for correcting an advance of the earth working device to compensate for a deviation from the drilling course.
 7. The apparatus of claim 3 , wherein the valves are spring-biased valves.
 8. The apparatus of claim 2, wherein the fluid is bentonite.
 9. The apparatus of claim 2 for carrying out any one of the operations selected from the group consisting of correcting a deviation of a drill head in a pilot bore, when the earth working machine is the drill head, correcting a deviation of an expansion head, when the earth working machine is the expansion head and lines are pulled in, opening and closing of valves or gates, operation of borehole tools, disengagement or engagement of tools in the ground, and moving out of a bore route for establishing branch lines or for exploration.
 10. A method for operating an actuator for controlling an earth working device, comprising the steps of: subjecting the actuator to a fluid selected from the group consisting of drilling medium and flushing medium and used as the fluid for the earth working device; and controlling an operation of a valve assembly such that the drilling or flushing medium is retained in the actuator, while at the same time is supplied to the earth working device for executing a desired operation.
 11. The method of claim 10, wherein the earth working device is a drill head or expansion head.
 12. The method of claim 10, wherein the controlling step includes the step of actuating a separate switch for adjusting the operation of the valve assembly.
 13. The method of claim 10, wherein the valve assembly includes plural spring-biased valves which return to their initial position when a pressure of the drilling or flushing medium drops below a spring force which acts on the valves. 